The invention concerns a process to use alphanumeric characters for call numbers for connections and for signaling within and between telecommunications networks (call by name).
The calling methods in telecommunications networks for fixed-lines networks have progressed from impulse dialing methods (manual connection, rotary dial switching, push-button set module) via multiple frequency methods to digital signaling methods, such as the D-channel DSS1 protocol (Ref. 1) within the Integrated Services Digital Network ISDN (Ref. 2).
Here the dialing method relies on the use of the numerical sequence 0 . . . 9, where the decimal dialing categories form the corresponding hierarchical network topology. Thus, the digit “0” is generally used as the traffic separator for access to the long-distance network, where the subsequent digit identifies the top network level of one of 9 regions (1 . . . 9=9 regions). The input of additional digits identifies successively subordinated network hierarchical levels (regional switching centers, local switching centers, etc). Subsequent additions, such as the development of private telecommunications networks, specific service numbers, etc., further limit the supply of numbers, by reserving certain blocks of numbers for specific purposes. For example, the number 0171 is used to access the D1 mobile network, the number 0800 is reserved for service purposes, etc. This is necessary because the supply of numbers and the (reasonable) maximum number of digits possible in a decimal system are limited.
This method was standardized internationally by CCITT, later ITU or ETSI, and it was maintained for reasons of compatibility in the digital networks, such as the ISDN network or the GSM network. This guarantees in principle that all end users can reach each other, regardless of the signaling technology and terminals.
The method in principle of this numerical signaling method is defined in the international numbering plan (Ref. 3). This also specifies the maximum number of digits and their division into country code (CC), national destination code (NDC), and subscriber number (SN) on an international level, where the maximum number of digits of a call number on an international level is limited to 15 digits.
The digital signaling system DSS1 in the ISDN network should be seen as the reference system for all modern digital signaling systems. In principle, all corresponding modifications or augmentations of corresponding signaling methods, such as for the GSM network, are derived from it. The same applies by implication for the signaling method between the switching centers of a network or internationally between switching networks. All modern signaling systems are based on the digital signaling system SS7 (Central Channel Signaling System No. 7, Ref. 14).
Thus, the air interface of modern cellular mobile telephone networks, such as the GSM network, uses a modified DSS1 protocol architecture on level 3, ISDN switching centers and an appropriately augmented SS7 signal in the switching area, where the method in connection and service management is largely identical to that of the ISDN network, but where it is specifically augmented by mobility management specific to mobile telephone communication and guaranteed transmission in the air interface. This method (Ref. 4, starting on page 118) assures an optimally fast development of standards and networks plus, among others, common services, such as call forwarding, conference calls etc. between mobile telephone networks and fixed networks.
However, the current numerical dialing method contains additional disadvantages, which are explained in the following.
The maximum number of digits is set internationally (see above). Thus, after subtracting the international access codes, the country code, the domestic destination code, the local destination codes and the subscriber number, at most 4 digits remain for direct dialing into private telecommunications networks (direct dialing to an extension).
In the US, where long numbers were the norm very early on due to the large number of subscriber connections in the urban areas (for example New York), the telephone keys (or the numerical switches) were also labeled with letters, where each digit from 1–9 was normally associated with 3 letters of the alphabet (FIG. 1). Thus, a telephone number could be shown as a combination of letters and numbers, which, in the opinion of some experts, was easier to be memorized than a string of numbers. Using the same argument, the license plates of automobiles in Germany were designed to use strings of letters and numbers. However, such labeling does not modify the decimal telephone dialing method, because the mere label does not enlarge the supply of numbers available for dialing.
The multiple labeling of the keys also makes it feasible in principle to use “alphabetic dialing” (FIG. 1). For example, a firm named “HUT GmbH and Co KG” could be dialed using the three digits 4-8-8 (HUT). As FIG. 4 shows, this method is also used in Germany. For example, network-independent call numbers (beginning with 0700 . . . ) are offered by providers or service call numbers (beginning with 0800 . . . ) are offered by Telekom.
The problem with these so-called vanity call numbers is that this method can lead to conflicts by the several-to-one relationship of letters to numerical digits and to problems in the number of digits dialed.
For example, under the several-to-one relationship, the firm “GUT” would have the same digital number as the firm HUT of the previous example. Furthermore, a shortened call number blocks all longer call numbers that have the same initial numeric string. Assuming a nine-digit call number, the firm HUT of the previous example would block the last 6 digits (00 00 01 to 99 99 99), i.e. this would block a set of call numbers of almost a million subscribers. This is the reason, why the so-called vanity numbers are marketed in the USA at such high prices. The problem of blocked numbers derives from continuing to dial numbers, regardless of how the keys or dialing wheels are labeled. Using single number dialing, the network has no criteria to determine the end of the dialed number, so that the network cannot recognize the name HUTFEDER by this method. The string FEDER would in this case be treated as dialing the corresponding digits 33337 after connecting to the switchboard of the subscriber HUT (488). It is not possible to dial any other subscriber in this case.
An alternative to this loss of call numbers due to short vanity call numbers uses a vanity call number for a firm or a person as a personal call number with a defined length based upon the network hierarchy. At least this method will not block any longer call numbers.
However, such a method is usually only of limited usefulness, as will be shown in the following. Thus, in the previous example, the firm “HUT”, which may be located in a metropolis like Berlin with nine digit telephone numbers, would need to specify six additional digits or letters to complete its identification. If this is a large firm with two reserved digits for direct dialing, then the call number is shortened by two digits. One could then use, for example, HUTBERL0 or HUTGMBH0 to refer to the firm HUT in Berlin, where the ending “0” refers to the switchboard of firm HUT. However, the impact of such a call number is rather questionable. Nobody familiar with the firm HUT would associate such a vanity call number with the firm. The example shows that a vanity call number is very unlikely to work in the case of a direct-dial company telecommunication system. Use of the current vanity method for alphabetic dialing is thus restricted to a network-wide call number for a service or sales contact office, for example.
The listed examples may be abstract, but the problem can be identified by presuming to use the method with well-known firms, such as IBM, Bosch, Siemens, or firms with a longer name, such as “DeTeMobil Deutsche Telekom Mobilnet GmbH”. Here one will quickly see that the vanity method cannot yield the intended result of intuitive dialing based on the name, given the current length of call numbers. This also applies to the use of names in the private sector. Given that there are numerous persons with identical names as others, the applicability will be limited. The probability of inappropriate connections will likely rise dramatically, if one wishes to reach Mr. “Maier”, first name “Werner”, in “Berlin” with an unknown call number, particularly if the caller does not know the length of the phone numbers used in Berlin.
The Internet now commonly uses a better method that does not need to rely on historical precedence and the parallel existence of current infrastructure and subscriber phones. Thanks to the common PC keyboard, alphanumeric addresses of any length may be used based on the Uniform Resource Locator URL (Ref. 5), which has very few restrictions of the type listed above. An Internet router can perfectly well distinguish the address HUT.de from the address HUTFEDER.de. The only restriction is that there cannot be multiple firms of the same name in the same domain (for example, the same country). There is an additional disadvantage from the immediate connection established whenever the name is input (URL address input via Internet browser). Even though this is no problem in principle in the Internet, downloading the wrong web pages generates unnecessary costs and lost time from the transfer of undesired information. In the case of voice or data connections, such erroneous connections leads to unintended problems and unnecessary connection costs. This may be demonstrated easily by means of an e-mail connection. For example, the e-mail addresses “Mister.President@T-Online.de”, “MisterPresident@T-Online.de”and “Mister-President@T-Online.de” are clearly three different names or Presidents. Transfer of e-mail with attachments can easily lead to problems in cases of name confusion. This shows the disadvantages of alphanumeric address methods where there is no possibility to identify the target participant prior to the exchange of information.
U.S. Pat. No. 5,485,512 identifies a method to use alphanumeric characters as call numbers to establish connections within and between telecommunication networks, where an alphanumeric subscriber call number is used for dialing by name, rather than the usual decimal number. The length and the characters used in the character string may be essentially freely defined by the subscriber. Because only the alphanumeric character string is used to establish the connection, the use of the proposed system requires substantial costs, as all technical installations of the telecommunication system in question starting from the switching center will need to be retrofitted.